Quality control of ²²³Ra eluate

Czech version

Authors: Anna Bajzíková; Ján Kozempel; Martin Vlk; Ekaterina Kukleva; Petra Mičolová
Authors‘ workplace: Fakulta jaderná a fyzikálně inženýrská, Katedra jaderné chemie, ČVUT v Praze, ČR
Published in: NuklMed 2016;5:22-26
Category: Original Article

Overview

Introduction:
The use of radionuclides plays an irreplaceable role in medicine. Their usage is under the control of Law on Pharmaceuticals and other regulations including standardized operational procedures. The quality control of the radionuclides always includes the radionuclidic purity test. For ²²³Ra (T_1/2 = 11,435 days), it may be carried out by alpha and gamma spectrometry. Particular care have to be taken of long half-life nuclides, e.g. the ²²⁷Ac (T_1/2 = 21,773 years) or the ²²⁷Th (T_1/2 = 18,72 days).

Methods:
The ²²³Ra was eluted from ²²⁷Ac/²²⁷Th/²²³Ra generator (²²⁷Ac on an ion exchanger Dowex-1). The elution was carried out in optimal conditions (0,7M HNO₃ and 80% MeOH) and in conditions that simulated the presence of radionuclidic impurities. Generator eluates were analyzed by alpha and gamma spectrometry and an alternative control method employing the ²²³Ra analysis by paper chromatography was tested. Measurement on NaI(Tl) crystal was performed with developed paper strips (TODGA impregnated paper Whatman-1, mobile phase 1M HNO₃).

Results:
The purity of eluates was cross-checked by alpha and gamma spectrometry and by paper chromatography. The mixture of ²²⁷Ac/²²⁷Th/²²³Ra was successfully separated and measured on TLC scanner. In optimal elution conditions the ²²³Ra and its daughter nuclides (²¹⁹Rn, ²¹⁵Po, ²¹¹Pb) were detected. In the radionuclidic impurities simulated elution the ²²⁷Th was also detected. In both cases the levels of radionuclidic impurities did not exceed 3,5 %.

Conclusion:
The purity of ²²³Ra radionuclide in both types of conditions was higher than 96 %. These results were confirmed by all selected methods of analysis. The paper chromatography is suitable alternative method for ²²⁷Ac/²²⁷Th/²²³Ra mixtures separation and analysis. This method can be used for the determination of ²²³Ra radionuclidic purity after a simple validation.

Key Words:
²²³Ra, radionuclidic purity, spectrometry, paper chromatography, quality control

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